Monochromatic light sources of red (R), green (G), and blue (B) have been used for application of a variety of displays, the light sources generating a white light output having excellent color balance. For example, an SHG laser formed of a solid state laser, a nonlinear optical crystal, etc. is used for a RGB light source used for a transmissive liquid crystal display.
This SHG laser irradiates the solid state laser with excitation light emitted from a semiconductor laser, causes a fundamental wave oscillated by the solid state laser to enter the subsequent nonlinear optical crystal, thus obtains laser beams of oscillation wavelengths of RGB by using a second harmonic or the like extracted from the nonlinear optical crystal. In order to form the respective light sources of RGB, it is necessary to change a kind of the solid state laser and a kind of the nonlinear optical crystal for R, G, and B (for example, see Patent Document 1).    Patent document 1: Japanese Patent Application Publication No. 2006-66818